i've bought the game but have been looking around for the commands to install linux games but i've either been told to install steam or been given the coding without the command to start it.

would appreciate the command needed 

1) Unpack the .zip archive with Guilty Force on your Linux somewhere;

2) Find GuiltyForce.x86_64 file;

3) Click on its properties and make sure that you can run the x86_64 file as an executable;

4) Run this file as an executable, for example with a command like ./"GuiltyForce.x86_64"

5) Enjoy! (64-bit version of Linux is mandatory)